Project Summary Recently breakthroughs in gene editing technology have revolutionized many fields of biological and biomedical research, enabling applications including large-scale tagging of endogenous genes or editing of non-coding genomic elements. Screening of edited cell lines for those containing the correct edits, however, have mostly relied on the classical clonal selection method, which is slow and resource-intensive. Here, we propose to develop an enzymatic amplification technique inside living cells to report 1) the expression of a low abundance protein and 2) a single copy of specific DNA sequence in the genome. This technique will enable rapid isolation of edited cells by simple fluorescence-based cell sorting, thus greatly enhancing the efficiency and accessibility of gene editing for cell lines.